Mexican-American War (1846–1848): Conquest and Consequence

Introduction: Two Perspectives on the War

From the perspective of the United States, the Mexican-American War, together with the Louisiana Purchase, represented an important land acquisition as part of the country's relentless expansion westward. In this regard, Kurth (1996) reports that "there were grand achievements in this national project of continental expansion, especially the southwestern annexations, which were achieved through U.S. military victory in the Mexican-American War. In this case, the United States took advantage of the fact that Britain and France were disrupted by serious internal turmoil."

With Britain and France otherwise occupied with their more immediate domestic issues, the United States was free to pursue its expansionist Manifest Destiny plans for the western regions of the country, including most especially California and its vast resources and temperate climate.

From the perspective of Mexico, however, the invasion by the United States was a heavy-handed blow by an international bully that had provoked a war simply to acquire land. The U.S. invasion of Mexico in 1846 resulted in the 1848 Treaty of Guadalupe Hidalgo, which secured an enormous amount of territory from Mexico — including Texas, New Mexico, and California — for the United States.

The Great Territorial Loss

Not surprisingly, this humiliating defeat has been the source of longstanding bitterness against the United States on the part of Mexico. The Mexican-American War, fought between the United States and Mexico, is described by Reiter as involving "a semi-exclusionary, moderately repressive regime fighting a long losing war."

The Treaty of Guadalupe Hidalgo effectively redrew the map of North America, transferring approximately half of Mexico's territory to the United States. The sheer scale of this territorial loss made the war one of the most consequential events in Mexican national history, and its legacy continues to shape the relationship between the two countries.

The Aftermath for Mexico

Following Mexico's loss to the United States, Mexican president Antonio López de Santa Anna fled to Venezuela in exile. His end, however, was not as ignominious as that act might suggest. Reiter reports that "Santa Anna resigned the presidency voluntarily, he did so while the war was ongoing (September 1847), and even after he resigned as president he kept his position as leader of Mexico's army."

Although the new Mexican president, Manuel Peña y Peña — who had been appointed by Santa Anna — eventually relieved Santa Anna of his commander-in-chief position, Santa Anna took refuge in Venezuela to avoid the impending court martial. The political turbulence that followed the war underscored just how devastating the defeat had been for Mexico's institutions as well as its territory.

The Issue of Slavery in the New Territories

Having acquired enormous territories in the West by virtue of the peace treaty signed with Mexico following the end of the Mexican-American War in 1848, the status of these new territories became the focus of intense debate between Southern and Northern states on the issue of slavery. According to Huston, "Southerners demanded the privilege of taking slavery into the new territories if the environment permitted profitable undertakings; Northerners wanted slavery absolutely and explicitly excluded from them."

Although comprising a single purportedly united country, the Northern and Southern states were at two extremes in terms of their economies and views about slavery. Following the end of the Mexican War, the United States was larger in geographic size, but the country had added all of this new territory during a period in its history when states' rights concerning slavery were at the forefront of national debate. Increased sectionalism threatened to expand slavery into these territories, and the proviso offered by David Wilmot in 1846 — which would restrict slavery to its then-existing boundaries — was intended to allow the country to develop under this fraught status quo without further inflaming tensions.

The fundamental issues involved, however, did not readily lend themselves to so straightforward a solution. Huston emphasizes that "Northerners often did not react like Lincoln in seeing a demise of slavery by some natural mechanism; instead, they pictured a more complicated scenario."

Conversely, the overarching concerns from the perspective of slave-owning states were more pragmatic and immediate. According to Huston, "Most important, Southerners, though exhibiting some confusion in their predictions, believed that limiting slavery to its existing boundaries would produce poverty, depopulation of whites, and ultimately race war."

Clearly, the South's perspective was overwhelmingly economic in nature but political in tone, while the North's perspective was political in nature but economic in effect. With so much at stake, it is little wonder that two such divergent perspectives emerged in response to the Wilmot Proviso of 1846. Huston emphasizes that "in their search for an understanding of what the future might bring under the Wilmot prohibition, Southerners were misled by classical economic theory; and thus they read into the Wilmot Proviso a more grim outcome than was likely."

References

Coward, John M. "Dispatches from the Mexican War." Journalism History 26, no. 1 (Spring 2000): 39.

Huston, James L. "Southerners against Secession: The Arguments of the Constitutional Unionists in 1850–51." Civil War History 46, no. 4 (December 2000): 280–291.

Huston, James L. "Theory's Failure: Malthusian Population Theory and the Projected Demise of Slavery." Civil War History 55, no. 3 (September 2009): 354–361.

Kurth, James. "America's Grand Strategy." The National Interest 43 (Spring 1996): 3–9.

"The Mexican-American War." Public Broadcasting Service Special Features. Available: http://www.pbs.org/wgbh/americanexperience/features/general-article/grant-mexican-american-war/.

Reiter, Dan. How Wars End. Princeton, NJ: Princeton University Press, 2009.

Varon, Elizabeth R. Disunion! The Coming of the American Civil War, 1789–1859. Chapel Hill, NC: University of North Carolina Press, 2008.

Yoo, John. "Exercising Wartime Powers: The Need for a Strong Executive." Harvard International Review 28, no. 1 (Spring 2006): 22–25.